.
Links ¶
- Decipher 2021: Writing Smart Contracts with Python
- PyTeal's ReadTheDocs
- Algorand Developer Portal
- ARC-4
- Box / AVM-8 consensus params
- Beaker
.
Algorand dApp Layers ¶
PyTeal: Boxes and ABI-Compatible Smart Contracts¶
Polling App ¶
.
Let's Take a Poll On Chain¶
.
.
Example¶
submit choice Burj Khalifa - Dubai¶
.
Problem: We don't want any account to have more influence than other accounts¶
END-RESULT: ✅ Taipei += 1 ✅¶
.
END-RESULT: ✅ Shanghai += 1 ✅¶
.
END-RESULT: ❌ Merdeka += 26 ❌¶
.
Each account only contributes to $\leq$ 1 choice¶
.
Can we store each account in global storage?¶
Yes, BUT limited to 8KB which is only 256 accounts (if not compressing)¶
.
.
Anything else we could do (now on mainnet) ?¶
UNLIMITED assets and apps can be associated with any account, including poll's app account¶
Notes:
- expensive 0.1 Algos / acct vs. 0.0157 Algos / acct w/ boxes
- complicated / error prone
- need to keep track of asset id off chain and supply it as a foreign ref, then parse out URL, verify that first 32 bytes are the account, etc...
- need to group with
Asset Config Txnwhich specifies how the URL changes
.
SOLUTION ¶
.
In [5]:
%%script false --no-raise-error
choice = Bytes(b"\x01") # "2. Burj Khalifa - Dubai
option_count_prefix = b"option_count_" # TODO: replace the option_count_keys[0] stuff below
new_choice_count_key = ScratchVar(TealType.bytes)
old_choice_count_key = ScratchVar(TealType.bytes)
submission_expr = Seq(
Assert(Btoi(choice) < Int(7)),
new_choice_count_key.store(
SetByte(option_count_keys[0], Int(len(option_count_prefix)), choice.get())
),
# ### BOXES BEGIN ### #
sender_box := App.box_get(Txn.sender()),
If(sender_box.hasValue()).Then(
# the sender has already submitted a response, so it must be cleared
Assert(App.globalGet(resubmit_key)),
old_choice_count_key.store(
SetByte(
option_count_keys[0],
Int(len(option_count_prefix)),
Btoi(sender_box.value()),
)
),
App.globalPut(
old_choice_count_key.load(),
App.globalGet(old_choice_count_key.load()) - Int(1),
),
),
App.box_put(Txn.sender(), choice.encode()),
# ### BOXES END ### #
App.globalPut(
new_choice_count_key.load(),
App.globalGet(new_choice_count_key.load()) + Int(1),
),
)
methods - allow interacting with Poll App¶
(didn't include delete for reasons to be explained shortly)¶
.
Refresher - OnComplete Actions for App Transactions¶
| Value | Name | Description |
|---|---|---|
| 0 | NoOp | Execute ApprovalProgram only |
| 1 | OptIn | Allocate local state and execute ApprovalProgram |
| 2 | CloseOut | Execute ApprovalProgram and clear local state |
| 3 | ClearState | Execute ClearStateProgram and clear locals (even if rejects) |
| 4 | UpdateApplication | Execute ApprovalProgram and update programs |
| 5 | DeleteApplication | Execute ApprovalProgram and delete the app |
.
PyTeal's Router: Building an ARC-4 Application¶
.
.
Definition: a Router and its M.O.E. Questions¶
.
Definition: a Router and its M.O.E. Questions¶
PyTeal's Router constructs the Teal code necessary to delegate application transactions to either a bare app call action or a method based on answers to:¶
1 [M]. In a bare app call? If not, which method selected?¶
2 [O]. Which OnComplete is requested?¶
3 [E]. This app already exists? (Conversely, being created?)¶
.
PyTeal's Router: Building an ARC-4 Application¶
.
.
.
.
Router Initialization¶
In [6]:
# WARNING: STUBS ARE FOR ROUTER-ILLUSTRATION PURPOSES ONLY!!!
del_action = OnCompleteAction.call_only(Seq())
router = Router(
name="OpenPollingApp",
descr="This is a polling application.",
bare_calls=BareCallActions(delete_application=del_action),
)
.
Compile¶
approval, clear, json_contract = router.compile_program(version=8)
JSON Contract (with no methods)¶
In [8]:
print(json.dumps(json_contract.dictify(), indent=2))
{
"name": "OpenPollingApp",
"methods": [],
"networks": {},
"desc": "This is a polling application."
}
.
Compile¶
approval, clear, json_contract = router.compile_program(version=8)
In [9]:
print(approval)
#pragma version 8 txn NumAppArgs int 0 == bnz main_l2 err main_l2: txn OnCompletion int DeleteApplication == bnz main_l4 err main_l4: txn ApplicationID int 0 != assert int 1 return
.
Routing bare app call delete¶
In [12]:
show() # custom method showing relevant Teal
txn NumAppArgs
int 0
==
bnz main_l2
. . .
main_l2:
txn OnCompletion
int DeleteApplication
==
bnz main_l4
. . .
main_l4:
txn ApplicationID
int 0
!=
assert
int 1
return
.
Append methods to route with @router.method¶
.
In [13]:
@router.method(name="open")
def open_poll() -> Expr:
"""Marks this poll as open."""
return Seq()
@router.method(name="close")
def close_poll() -> Expr:
"""Marks this poll as closed."""
return Seq()
.
In [14]:
approval, clear, json_contract = router.compile_program(version=8)
In [15]:
print(json.dumps(json_contract.dictify(), indent=2))
{
"name": "OpenPollingApp",
"methods": [
{
"name": "open",
"args": [],
"returns": {
"type": "void"
},
"desc": "Marks this poll as open."
},
{
"name": "close",
"args": [],
"returns": {
"type": "void"
},
"desc": "Marks this poll as closed."
}
],
"networks": {},
"desc": "This is a polling application."
}
Approval Program - Routing to open and close¶
In [19]:
show()
txna ApplicationArgs 0
method "open()void"
==
bnz main_l5
. . .
txna ApplicationArgs 0
method "close()void"
==
bnz main_l4
. . .
main_l5:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
!=
&&
assert
callsub open_0
. . .
main_l4:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
!=
&&
assert
callsub close_1
. . .
// open
open_0:
retsub
. . .
// close
close_1:
retsub
ABI Types¶
.
PyTeal Type |
ARC-4 Type |
Dynamic / Static |
Description |
|---|---|---|---|
|
Static |
An 8-bit unsigned integer |
|
|
IFF |
A fixed-length array with N elements |
|
|
Dynamic |
Variable-length byte array |
.
Add a method with ABI arguments but no returns¶
In [20]:
@router.method
def submit(choice: abi.Uint8) -> Expr:
"""Submit a response to the poll.
Args:
choice: The choice made by the sender.
"""
return Seq()
.
In [21]:
opts = OptimizeOptions(scratch_slots=True)
approval, clear, json_contract = router.compile_program(version=8, optimize=opts)
# -----------------------------------------------------------------^^^^^^^^^^^^^
JSON Contract - method submit()¶
In [25]:
show() # lines 20-33 of the JSON contract
{
"name": "submit",
"args": [
{
"type": "uint8",
"name": "choice",
"desc": "The choice made by the sender."
}
],
"returns": {
"type": "void"
},
"desc": "Submit a response to the poll."
}
.
Routing submit(choice)¶
In [29]:
show()
txna ApplicationArgs 0
method "submit(uint8)void"
==
bnz main_l5
. . .
main_l5:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
!=
&&
assert
txna ApplicationArgs 1
int 0
getbyte
callsub submit_2
. . .
// submit
submit_2:
store 0
retsub
.
.
The Actual Program¶
In [39]:
show()
def on_delete() -> Expr:
return Assert(Txn.sender() == Global.creator_address())
router = Router(
name="OpenPollingApp",
descr="A polling application with no restrictions on who can participate.",
bare_calls=BareCallActions(
delete_application=OnCompleteAction.call_only(on_delete())
),
)
open_key = Bytes(b"open")
resubmit_key = Bytes(b"resubmit")
option_name_prefix = b"option_name_"
option_name_keys = [
Bytes(option_name_prefix + b" "),
Bytes(option_name_prefix + b""),
Bytes(option_name_prefix + b""),
]
option_count_prefix = b"option_count_"
option_count_keys = [
Bytes(option_count_prefix + b" "),
Bytes(option_count_prefix + b""),
Bytes(option_count_prefix + b""),
]
@router.method(no_op=CallConfig.CREATE)
def create(
options: abi.StaticArray[abi.String, Literal[3]], can_resubmit: abi.Bool
) -> Expr:
"""Create a new polling application.
Args:
options: A list of options for the poll. This list should not contain duplicate entries.
can_resubmit: Whether this poll allows accounts to change their submissions or not.
"""
name = abi.make(abi.String)
return Seq(
App.globalPut(open_key, Int(0)),
App.globalPut(resubmit_key, can_resubmit.get()),
name.set(options[0]),
App.globalPut(option_name_keys[0], name.get()),
App.globalPut(option_count_keys[0], Int(0)),
name.set(options[1]),
App.globalPut(option_name_keys[1], name.get()),
App.globalPut(option_count_keys[1], Int(0)),
name.set(options[2]),
App.globalPut(option_name_keys[2], name.get()),
App.globalPut(option_count_keys[2], Int(0)),
)
@router.method(name="open")
def open_poll() -> Expr:
"""Marks this poll as open.
This will fail if the poll is already open.
The poll must be open in order to receive user input.
"""
return Seq(
Assert(Not(App.globalGet(open_key))),
App.globalPut(open_key, Int(1)),
)
@router.method(name="close")
def close_poll() -> Expr:
"""Marks this poll as closed.
This will fail if the poll is already closed.
"""
return Seq(
Assert(App.globalGet(open_key)),
App.globalPut(open_key, Int(0)),
)
@router.method
def submit(choice: abi.Uint8) -> Expr:
"""Submit a response to the poll.
Submissions can only be received if the poll is open. If the poll is closed, this will fail.
If a submission has already been made by the sender and the poll allows resubmissions, the
sender's choice will be updated to the most recent submission. If the poll does not allow
resubmissions, this action will fail.
Args:
choice: The choice made by the sender. This must be an index into the options for this poll.
"""
new_choice_count_key = ScratchVar(TealType.bytes)
old_choice_count_key = ScratchVar(TealType.bytes)
return Seq(
Assert(choice.get() < Int(3)),
new_choice_count_key.store(
SetByte(option_count_keys[0], Int(len(option_count_prefix)), choice.get())
),
# ### BOXES BEGIN ### #
sender_box := App.box_get(Txn.sender()),
If(sender_box.hasValue()).Then(
# the sender has already submitted a response, so it must be cleared
Assert(App.globalGet(resubmit_key)),
old_choice_count_key.store(
SetByte(
option_count_keys[0],
Int(len(option_count_prefix)),
Btoi(sender_box.value()),
)
),
App.globalPut(
old_choice_count_key.load(),
App.globalGet(old_choice_count_key.load()) - Int(1),
),
),
App.box_put(Txn.sender(), choice.encode()),
# ### BOXES END ### #
App.globalPut(
new_choice_count_key.load(),
App.globalGet(new_choice_count_key.load()) + Int(1),
),
)
class PollStatus(abi.NamedTuple):
can_resubmit: abi.Field[abi.Bool]
is_open: abi.Field[abi.Bool]
results: abi.Field[abi.StaticArray[abi.Tuple2[abi.String, abi.Uint64], Literal[3]]]
@router.method
def status(*, output: PollStatus) -> Expr:
"""Get the status of this poll.
Returns:
A tuple containing the following information, in order: whether the poll allows
resubmission, whether the poll is open, and an array of the poll's current results. This
array contains one entry per option, and each entry is a tuple of that option's value and
the number of accounts who have voted for it.
"""
can_resubmit = abi.make(abi.Bool)
is_open = abi.make(abi.Bool)
option_name = abi.make(abi.String)
option_count = abi.make(abi.Uint64)
partial_results = [
abi.make(abi.Tuple2[abi.String, abi.Uint64]),
abi.make(abi.Tuple2[abi.String, abi.Uint64]),
abi.make(abi.Tuple2[abi.String, abi.Uint64]),
]
results = abi.make(abi.StaticArray[abi.Tuple2[abi.String, abi.Uint64], Literal[3]])
return Seq(
can_resubmit.set(App.globalGet(resubmit_key)),
is_open.set(App.globalGet(open_key)),
option_name.set(App.globalGet(option_name_keys[0])),
option_count.set(App.globalGet(option_count_keys[0])),
partial_results[0].set(option_name, option_count),
option_name.set(App.globalGet(option_name_keys[1])),
option_count.set(App.globalGet(option_count_keys[1])),
partial_results[1].set(option_name, option_count),
option_name.set(App.globalGet(option_name_keys[2])),
option_count.set(App.globalGet(option_count_keys[2])),
partial_results[2].set(option_name, option_count),
results.set([partial_results[0], partial_results[1], partial_results[2]]),
output.set(can_resubmit, is_open, results),
)
In [40]:
approval, clear, json_contract = router.compile_program(version=8, optimize=opts)
JSON Contract Stub - COMPLETE¶
In [44]:
show()
{
"name": "OpenPollingApp",
"methods": [
{
"name": "create",
"args": [
{
"type": "string[3]",
"name": "options",
"desc": "A list of options for the poll. This list should not contain duplicate entries."
},
{
"type": "bool",
"name": "can_resubmit",
"desc": "Whether this poll allows accounts to change their submissions or not."
}
],
"returns": {
"type": "void"
},
"desc": "Create a new polling application."
},
{
"name": "open",
"args": [],
"returns": {
"type": "void"
},
"desc": "Marks this poll as open.\nThis will fail if the poll is already open.\nThe poll must be open in order to receive user input."
},
{
"name": "close",
"args": [],
"returns": {
"type": "void"
},
"desc": "Marks this poll as closed.\nThis will fail if the poll is already closed."
},
{
"name": "submit",
"args": [
{
"type": "uint8",
"name": "choice",
"desc": "The choice made by the sender. This must be an index into the options for this poll."
}
],
"returns": {
"type": "void"
},
"desc": "Submit a response to the poll.\nSubmissions can only be received if the poll is open. If the poll is closed, this will fail.\nIf a submission has already been made by the sender and the poll allows resubmissions, the sender's choice will be updated to the most recent submission. If the poll does not allow resubmissions, this action will fail."
},
{
"name": "status",
"args": [],
"returns": {
"type": "(bool,bool,(string,uint64)[3])",
"desc": "A tuple containing the following information, in order: whether the poll allows resubmission, whether the poll is open, and an array of the poll's current results. This array contains one entry per option, and each entry is a tuple of that option's value and the number of accounts who have voted for it."
},
"desc": "Get the status of this poll."
}
],
"networks": {},
"desc": "A polling application with no restrictions on who can participate."
}
In [48]:
show()
#pragma version 8
txn NumAppArgs
int 0
==
bnz main_l12
txna ApplicationArgs 0
method "create(string[3],bool)void"
==
bnz main_l11
txna ApplicationArgs 0
method "open()void"
==
bnz main_l10
txna ApplicationArgs 0
method "close()void"
==
bnz main_l9
txna ApplicationArgs 0
method "submit(uint8)void"
==
bnz main_l8
txna ApplicationArgs 0
method "status()(bool,bool,(string,uint64)[3])"
==
bnz main_l7
err
main_l7:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
!=
&&
assert
callsub status_4
store 2
byte 0x151f7c75
load 2
concat
log
int 1
return
main_l8:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
!=
&&
assert
txna ApplicationArgs 1
int 0
getbyte
callsub submit_3
int 1
return
main_l9:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
!=
&&
assert
callsub close_2
int 1
return
main_l10:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
!=
&&
assert
callsub open_1
int 1
return
main_l11:
txn OnCompletion
int NoOp
==
txn ApplicationID
int 0
==
&&
assert
txna ApplicationArgs 1
store 0
txna ApplicationArgs 2
int 0
int 8
*
getbit
store 1
load 0
load 1
callsub create_0
int 1
return
main_l12:
txn OnCompletion
int DeleteApplication
==
bnz main_l14
err
main_l14:
txn ApplicationID
int 0
!=
assert
txn Sender
global CreatorAddress
==
assert
int 1
return
// create
create_0:
store 20
store 19
byte 0x6f70656e
int 0
app_global_put
byte 0x72657375626d6974
load 20
app_global_put
load 19
load 19
int 2
int 0
*
extract_uint16
int 0
int 1
+
int 3
==
bnz create_0_l8
load 19
int 2
int 0
*
int 2
+
extract_uint16
create_0_l2:
substring3
store 21
byte 0x6f7074696f6e5f6e616d655f00
load 21
extract 2 0
app_global_put
byte 0x6f7074696f6e5f636f756e745f00
int 0
app_global_put
load 19
load 19
int 2
int 1
*
extract_uint16
int 1
int 1
+
int 3
==
bnz create_0_l7
load 19
int 2
int 1
*
int 2
+
extract_uint16
create_0_l4:
substring3
store 21
byte 0x6f7074696f6e5f6e616d655f01
load 21
extract 2 0
app_global_put
byte 0x6f7074696f6e5f636f756e745f01
int 0
app_global_put
load 19
load 19
int 2
int 2
*
extract_uint16
int 2
int 1
+
int 3
==
bnz create_0_l6
load 19
int 2
int 2
*
int 2
+
extract_uint16
b create_0_l9
create_0_l6:
load 19
len
b create_0_l9
create_0_l7:
load 19
len
b create_0_l4
create_0_l8:
load 19
len
b create_0_l2
create_0_l9:
substring3
store 21
byte 0x6f7074696f6e5f6e616d655f02
load 21
extract 2 0
app_global_put
byte 0x6f7074696f6e5f636f756e745f02
int 0
app_global_put
retsub
// open
open_1:
byte 0x6f70656e
app_global_get
!
assert
byte 0x6f70656e
int 1
app_global_put
retsub
// close
close_2:
byte 0x6f70656e
app_global_get
assert
byte 0x6f70656e
int 0
app_global_put
retsub
// submit
submit_3:
store 22
load 22
int 3
<
assert
byte 0x6f7074696f6e5f636f756e745f00
int 13
load 22
setbyte
store 23
txn Sender
box_get
store 26
store 25
load 26
bz submit_3_l2
byte 0x72657375626d6974
app_global_get
assert
byte 0x6f7074696f6e5f636f756e745f00
int 13
load 25
btoi
setbyte
store 24
load 24
load 24
app_global_get
int 1
-
app_global_put
submit_3_l2:
txn Sender
byte 0x00
int 0
load 22
setbyte
box_put
load 23
load 23
app_global_get
int 1
+
app_global_put
retsub
// status
status_4:
byte 0x72657375626d6974
app_global_get
!
!
store 3
byte 0x6f70656e
app_global_get
!
!
store 4
byte 0x6f7074696f6e5f6e616d655f00
app_global_get
store 5
load 5
len
itob
extract 6 0
load 5
concat
store 5
byte 0x6f7074696f6e5f636f756e745f00
app_global_get
store 6
load 5
store 11
int 10
itob
extract 6 0
load 6
itob
concat
load 11
concat
store 7
byte 0x6f7074696f6e5f6e616d655f01
app_global_get
store 5
load 5
len
itob
extract 6 0
load 5
concat
store 5
byte 0x6f7074696f6e5f636f756e745f01
app_global_get
store 6
load 5
store 12
int 10
itob
extract 6 0
load 6
itob
concat
load 12
concat
store 8
byte 0x6f7074696f6e5f6e616d655f02
app_global_get
store 5
load 5
len
itob
extract 6 0
load 5
concat
store 5
byte 0x6f7074696f6e5f636f756e745f02
app_global_get
store 6
load 5
store 13
int 10
itob
extract 6 0
load 6
itob
concat
load 13
concat
store 9
load 7
store 17
load 17
store 16
int 6
store 14
load 14
load 17
len
+
store 15
load 15
int 65536
<
assert
load 14
itob
extract 6 0
load 8
store 17
load 16
load 17
concat
store 16
load 15
store 14
load 14
load 17
len
+
store 15
load 15
int 65536
<
assert
load 14
itob
extract 6 0
concat
load 9
store 17
load 16
load 17
concat
store 16
load 15
store 14
load 14
itob
extract 6 0
concat
load 16
concat
store 10
byte 0x00
int 0
load 3
setbit
int 1
load 4
setbit
load 10
store 18
int 3
itob
extract 6 0
concat
load 18
concat
retsub